Tiny Holes:
Security cameras are small, and their most obvious giveaway is the lens
Think about where a camera would offer the best view. Inspect smoke detectors
Telltale Lights:
Most cameras have a tiny LED light that indicates recording.
Turn off all the lights in the room and scan for any faint, flickering lights
The Tech Approach:
If you're tech-savvy, you can use your phone's flashlight to scan electronic devices for a faint camera reflection off the lens.